Part 1. The Field of the Invention
This invention basically relates to novel, improved methods and apparatus for removing a marking from a stratum surface. Additionally, this invention relates to novel, improved methods and apparatus for correcting a marking on a surface by removing the marking and replacing it with another marking.
Part 2. Description of the Prior Art
The correction of markings such as written, typewritten or photodeposited markings on paper surfaces is well known to the art. Essentially, such corrections involve either initially removing the marking with an eraser or masking the marking with a correction fluid and replacing the removed or masked marking with another marking. Ideally, removal of the marking would represent the best approach for making such corrections. However, known erasers are notoriously ineffective for removing markings produced by pens, typewriters, or photodeposition apparatus. Such markings are extremely resistant to removal by erasers and are not satisfactorily removed unless excessive abrading force is used which adversely affects the quality of the substrate surface.
Correction fluids have been used extensively in the art as a preferred, more effective way to correct markings because of the shortcomings of erasers. Such correction fluids include an opacifying agent dispersed in a liquid which usually includes a soluble film-forming material. In use, the fluids are applied to the marking, allowed to dry, and a new marking is applied to the dried, coalesced residue of the fluid. Some disadvantages of correction fluids include the time required to apply and dry the fluid and incomplete masking of the marking usually because of "bleeding" resulting from interaction between the marking and the ingredients of the fluids which usually include an organic solvent. Another disadvantage is that the corrected marking is oftentimes detectable unless the coalesced residue of the fluid closely corresponds in texture and color of the substrate surface. Accordingly, there is an outstanding need in the art for a method which can quickly and effectively remove a marking from a surface without encountering the inconveniences involved in abrading or masking the marking. This invention is addressed to that need and provides an especially effective response to that need.